If you are a Telcel user, It avoids lines and fees.
Si prefieres pagar en efectivo, puedes acudir a una red extensa de comercios autorizados: Recarga Saldo Amigo Telcel | Hazlo en un Minuto
The genius of the recarga de saldo Telcel lies in its frictionless distribution. One does not need a branded store or a credit card. The top-up can be executed through a staggering variety of channels: at Oxxo (the ubiquitous convenience store chain that outnumbers nearly any other retail presence), at local abarrotes (corner stores), via electronic kiosks, through banking apps, or even via street vendors with portable terminals. Denominations are micro-targeted to the local economy—10, 20, 50, 100, 200 pesos. This granularity is critical. For a construction worker earning a daily wage, purchasing a 500-peso monthly package is impossible, but a 20-peso recarga (roughly $1 USD) buys enough data for a day’s worth of WhatsApp messages or a few calls home. The recarga is a cash-based, anonymous, and instant transaction, perfectly mirroring the informal cash economy in which half of Mexico’s workforce operates.
Telcel remains the undisputed king of connectivity in Mexico, and recharging your balance is a necessary ritual for millions. While the actual service (getting the data/calls) is reliable, the user experience varies wildly depending on how you choose to pay.